vtd: Fix ioapic interrupt remapping

vtd: Fix ioapic interrupt remapping

Besides io_apic_write(), io_apic_modify() also writes to io apic RTE.
This patch adds an intercept to remap interrupt in io_apic_modify().

In io_apic_read_remap_rte(), 'mask' value of RTE should not affect the
return value, so remove its checking.

Finally, remove panic() when index overflows. Instead, print error
messages and report back the failure to upper level.

Signed-off-by: Weidong Han <weidong.han@intel.com>